The audible frequency of rats is said to start from 200hz at the bottom and extend from 20Khz to 60Khz in the ultrasonic range.

This application is an application that generates a frequency specialized in the ultrasonic area and displays the waveform on the screen.

10 patterns of multiple frequency combinations
1500hz - 35000hz
15500hz - 35500hz
20000hz - 40000hz
20500hz - 40500hz
25000hz - 45000hz
25500hz - 45500hz
30000hz - 60000hz
30500hz - 60500hz
35000hz - 65000hz
35500hz - 65500hz

※ Notes
Depending on the nature of the device speaker, sound derived from high frequencies may be emitted.
Do not put your ear directly to the speaker of your device and listen to high frequency sound for a long time as it may harm your health.